diff --git a/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs b/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs
index d660cc4f9d..6d672d139f 100644
--- a/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs	
+++ b/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs	
@@ -108,7 +108,7 @@ namespace BizHawk.Emulation.Common
 
 		public override byte PeekByte(long addr)
 		{
-			if ((ulong)addr >= (ulong)Size)
+			if ((ulong)addr < (ulong)Size)
 				return ((byte*)Data)[addr ^ 1];
 			else
 				throw new ArgumentOutOfRangeException("addr");
@@ -117,8 +117,8 @@ namespace BizHawk.Emulation.Common
 		public override void PokeByte(long addr, byte val)
 		{
 			if (Writable)
-			{
-				if ((ulong)addr >= (ulong)Size)
+			{
+				if ((ulong)addr < (ulong)Size)
 					((byte*)Data)[addr ^ 1] = val;
 				else
 					throw new ArgumentOutOfRangeException("addr");